This stage involves the identification of alternative ways that the system could evolve in the future. How far into the future depends on the focal issue and the system; this study looked forward 15 years, as this was considered an appropriate length of time for both short term behaviours (e.g. patterns of effort allocation) and long term behaviours (e.g. investment in a fleet) to be influenced by the dynamics of the system. Although inherently uncertain, alternative futures should be plausible yet at the same time imaginatively push the boundaries of commonplace assumptions about the way in which the system will develop. These alternative futures should be based upon two or three uncertain or uncontrollable system drivers that have been determined in the previous assessment stage. For instance, uncertainties might arise from unknown behaviour of a group of actors, or from unknown dynamics in the natural or socio-economic components of the system.